There's not really any good reason to store an empty advice string
in an advice stash, but it's entirely possible that some people might
do it by accident. If they do that without this fix, restarting the
system will result in failure while reloading pg_stash_advice.tsv.
The root cause is that I (rhaas) did not think clearly enough when
defining pgsa_next_tsv_field(). After returning each field on the
line, it set *cursor to the start of the next field, and after
returning all of them, it set *cursor to the trailing NUL byte. But
when the last field on the line is empty, this is ambiguous: if we're
pointing at the trailing NUL byte, it could be either because it's the
start of the zero-length field or because we're out of fields. To
remove the ambiguity, this commit decides that *cursor will instead
be set to NULL when there are no more fields.
Reported-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/20260827171830.68.noahmisch@microsoft.com
Backpatch-through: 19
This is part of a more global effort to modernize the code tree with
safer allocation functions, which offer more protection in terms of:
- stronger type safety guarantees
- size overflow checks, particulary for arrays.
This set of updates includes allocation changes based on
palloc_object(), palloc_array() and repalloc_array(). This work is
similar to 1b105f9472, expanding more the new APIs in the tree in an
incremental fashion.
Author: Tristan Partin <tristan@partin.io>
Discussion: https://postgr.es/m/DKJB5887LGX9.359DV1UMZ1URK@partin.io
This is similar to d3bba04154, batching all the reports of this type
received since the last batch. This covers typos and inconsistencies
for the most part.
The user-visible documentation change impacts only HEAD.
This batch is similar to 462fe0ff62 and addresses a variety of code
style issues, including grammar mistakes, typos, inconsistent variable
names in function declarations, and incorrect function names in comments
and documentation. These fixes have accumulated on the community
mailing lists since the commit mentioned above.
Notably, Alexander Lakhin previously submitted a patch identifying many
of the trivial typos and grammar issues that had been reported on
pgsql-hackers. His patch covered a somewhat large portion of the issues
addressed here, though not all of them.
The documentation changes only affect HEAD.
If pg_stash_advice.persist = true, stashed advice will be written to
pg_stash_advice.tsv in the data directory, periodically and at
shutdown. On restart, stash modifications are locked out until this
file has been reloaded, but queries will not be, so there may be a
short window after startup during which previously-stashed advice is
not automatically applied.
Author: Robert Haas <rhaas@postgresql.org>
Co-authored-by: Lukas Fittl <lukas@fittl.com>
Discussion: https://postgr.es/m/CA+Tgmob87qsWa-VugofU6epuV0H5XjWZGMbQas4Q-ADKmvSyBg@mail.gmail.com
contrib/pg_stash_advice and src/test/modules/test_shmem
missed these, leading to complaints from git after an
in-tree check-world run.
Use our standard boilerplate list of ignorable subdirectories,
although the two modules presently create different subsets
of that.
This module allows plan advice strings to be provided automatically
from an in-memory advice stash. Advice stashes are stored in dynamic
shared memory and must be recreated and repopulated after a server
restart. If pg_stash_advice.stash_name is set to the name of an advice
stash, and if query identifiers are enabled, the query identifier
for each query will be looked up in the advice stash and the
associated advice string, if any, will be used each time that query
is planned.
Reviewed-by: Lukas Fittl <lukas@fittl.com>
Reviewed-by: Alexandra Wang <alexandra.wang.oss@gmail.com>
Reviewed-by: David G. Johnston <david.g.johnston@gmail.com>
Reviewed-by: Jakub Wartak <jakub.wartak@enterprisedb.com>
Discussion: http://postgr.es/m/CA+TgmoaeNuHXQ60P3ZZqJLrSjP3L1KYokW9kPfGbWDyt+1t=Ng@mail.gmail.com
